Caption: Electronic ink sign. Female researcher holding a sign printed with electronic ink. Materials coated in this ink can have text downloaded onto them electronically. The digital nature of the ink allows the text to be changed so a book, for example, can hold many titles. The ink consists of tiny transparent spheres containing microscopic white balls and a blue dye. When an electric current is applied, the balls, rise up through the blue dye and become visible, or sink. By controlling where they rise and where they sink, a message can be formed. The ink was developed by Joseph Jacobson at MIT, USA. The sign was made by E Ink, a company Jacobson co-founded.